This application claims priority to United Kingdom patent application number 0103837.1, filed Feb. 16, 2001, which is incorporated by reference along with all other references cited in this application.
This invention relates to modular computing systems based on integrated circuits such as field programmable gate arrays (FPGAs) which have complex and application dependent power supply requirements.
Modular systems are well known in the electronics industry. By defining a standardized mechanical and electrical interface to a printed circuit board manufactures and industry groupings guarantee compatibility between products from various vendors. Successful module standards attract large numbers of companies who provide a wide range of compatible modules. System integrators benefit by being able to mix-and-match from these modules to create an end system tailored to customer requirements. Commonly available modules include processing (for example, cards containing microprocessors and digital signal processors or DSPs), video capture, video display, digital-to-analog (D-to-A) conversion, and network connection. By making use of these off-the-shelf devices system integrators greatly reduce their engineering costs and can bring a product to market faster. Examples of successful module formats include the TRAM format proposed by INMOS for Transputer-based systems, Texas Instrument""s TIM40 format for digital signal processor (DSP) chips, Analog Devices SHARCPAC format for DSP chips and the PCI mezzanine card format.
Prior-art modular formats have been defined around the requirements of conventional microprocessors and digital signal processors. This naturally leads to bus based architectures which distribute address, data, and control signals from the processor or processors with or without additional point to point communicating sequential processes (CSP) links. Recently, field programmable gate arrays (FPGAs) have been making considerable inroads into the signal processing marketplace. FPGAs operate by implementing algorithms directly in reconfigurable logic gates: the functionality and interconnection of the logic gates is defined by a control memory which can be reprogrammed as required. With FPGAs there is no fixed bus based communications mechanism: instead programmable input/output blocks (IOBs) are configured to implement exactly those connections required by the application currently programmed onto the FPGA. Therefore, whereas a module standard for DSPs specifies the semantics of various signals on a bus a module standard based on FPGAs"" needs to deliver xe2x80x9crawxe2x80x9d digital connections between modules the semantics of which will be determined only once the FPGAs have been programmed. A module standard developed specifically for FPGAs by Nallatech Ltd., the assignee of the present invention is disclosed in the paper xe2x80x9cDIMExe2x80x94The first module standard for FPGA Based High Performance Computingxe2x80x9d by Malachy Devlin and Allan Cantle in Proceedings of FPL""99, Glasgow, UK September 1999, published as Springer LNCS 1673 which is incorporated by reference. The product documents xe2x80x9cDIME Module, Physical Level 0 Specification,xe2x80x9d part no. NT-301-0001 and xe2x80x9cVideo Processing, implementation Level 1 of the DIME Module,xe2x80x9d NT301-0002 (both available from Nallatech Ltd., Boolean House, One Napier Park, Cumbernauld, Glasgow G68 OBH, United Kingdom) provide more detailed information on the DIME modules and are incorporated by reference.
As silicon technology scales it is becoming necessary to change the power supply voltage for integrated circuits with each process shrink. For example, 0.5-micron line width integrated circuits generally operated off 5-volt supplies, 0.35-micron integrated circuits from 3.3-volt supplies, 0.25-micron integrated circuits from 2.5-volt supplies, and the present generation of 0.18-micron circuits from 1.8-volt supplies. Since a system is normally built from many different types of integrated circuits supplied by different vendors it is very likely that there will be multiple power supplies required and multiple voltage level standards for interchip signaling. It has become increasingly common for integrated circuits to operate their input/output pins at different voltage levels from their xe2x80x9ccorexe2x80x9d internal circuitryxe2x80x94this allows them to take advantage of improved process technology to increase performance while remaining compatible with older chip""s signaling voltages.
Intel Corporation reacted to the need for reducing power supply voltage as process technology improves by specifying an interface between a microprocessor and a programmable power supply as shown in FIG. 1. This allowed the microprocessor to specify the power supply voltage it required. One advantage of this technology was that personal computer motherboards could be upgraded with newer processors operating off a lower power supply voltage.
An additional trend in the industry has been an explosion in the number of electrical signaling standards used to communicate between digital chips. For many years only the transistor-transistor-logic (TTL) and complementary metal oxide semiconductor (CMOS) standards were of interestxe2x80x94and it was easy to convert between them. Today there are many different significant standards including TTL, CMOS, low voltage differential signaling (LVDS), low voltage positive emitter coupled logic (LVPECL), and gunning transceiver logic (GTL).
FPGA manufacturers have reacted to these problems by designing complex I/O structures which are xe2x80x9cbackwardly-compatiblexe2x80x9d with previous generations of process technology and can be programmed to support many different signaling standards. This has allowed FPGAs to become the xe2x80x9cuniversal connectorsxe2x80x9d at the board level which speak the signaling language of all the components in the system. The signaling standards and power supply requirements of a leading advanced FPGA family are described in xe2x80x9cVirtex-E 1.8V Extended Memory Field Programmable Gate Array""s xe2x80x9dPreliminary Product Specification, DS025 v1.2, Sep. 19, 2000 published by Xilinx Inc. which is incorporated by reference.
As shown in FIG. 2, modern FPGAs such as Virtex-E require multiple power supply voltages. As well as the xe2x80x9ccorexe2x80x9d power supply voltage groups or xe2x80x9cbanksxe2x80x9d of I/O pins can operate independently at different voltage levels. Some signaling schemes also require a xe2x80x9creferencexe2x80x9d voltage to set the threshold at which logical ones and zeros are recognized. More details on these aspects are found in the Xilinx product specification referenced above.
Prior art module standards have not addressed the need for multiple electrical signaling standards or the requirement for modules to operate off different supply voltages. In fact, one of the basic goals of prior-art modular standards is to specify the electrical signaling standards in great detail to guarantee compatibility. This is no longer necessary given FPGAs support for multiple signaling standards.
In the present invention a module standard for FPGAs is provided in which power supply voltages for daughtercards are not fixed in advance. Instead programmable power supplies are provided and a method is described by which each daughtercard can specify the required power supply voltage. Thus, unlike prior art systems, this modular system is backward and forward compatible with FPGA chips from many process generations allowing easy upgrading as new FPGA families become available.
A motherboard or baseboard for use with this invention includes a plurality of module connectors into which compatible modules or xe2x80x9cdaughtercardsxe2x80x9d can be plugged and a plurality of programmable power supplies. In a preferred embodiment there are four sets of module connectors and sixteen programmable power supplies. This allows each module to have four independently specifiable power supply voltages. A module may also connect several power supplies together in order to obtain higher current at a single voltage. Various schemes are described to ensure that the programmable power supplies will never deliver too high a voltage to the components on the modules.
In the context of this disclosure xe2x80x9cmotherboardxe2x80x9d or xe2x80x9cbaseboardxe2x80x9d is used to denote a printed circuit board, which may be of a standard format such as Double Eurocard, into which smaller xe2x80x9cdaughtercardsxe2x80x9d or xe2x80x9cmodulesxe2x80x9d can be plugged. It will be understood that there may be a hierarchy of xe2x80x9cmotherboardsxe2x80x9d and xe2x80x9cdaughterboardsxe2x80x9d in a system. In particular, it is likely that the motherboard itself will have connectors allowing it to be plugged into a backplane bus of some type (for example VME bus in industrial equipment or PCI bus in a personal computer). In the future the teachings of this invention may be applied to module standards with additional levels of motherboard/daughterboard hierarchy: for example, the daughterboards themselves may act as motherboards for even smaller daughterboards.
Although this invention is most suited for use with field programmable gate array (FPGA) chips such as those supplied by Xilinx Inc. and Altera Corp., it will be apparent to one skilled in the art that aspects of it could be used with many other classes of programmable devices, for example complex programmable logic devices (CPLDs) or programmable microprocessor peripherals. Recently, companies operating in the programmable logic industry such as Chameleon Systems Inc. have been introducing devices which combine aspects of processors and programmable logic: this invention is equally applicable to such new devices. The invention may also be applied to xe2x80x9csystem on a chipxe2x80x9d devices containing programmable logic and components such as microprocessors.
According to one embodiment, this invention provides a flexible modular standard for implementing digital systems using FPGAs. In further embodiment of this invention provides support for the complex power supply requirements of modern FPGAs. The invention also provides support for systems built from FPGAs and other components with differing power supply requirements.
Among the advantages of a preferred embodiment of this modular system are: (1) New FPGAs using a more modern process technology and a corresponding lower core power supply voltage are compatible with previous systems allowing users to take advantage of their increased density and performance. (2) The modular daughtercards remain simple and relatively low cost since programmable power supplies are provided on the baseboard. This makes upgrading the system more cost effective.
In one embodiment, the invention is an electronic system including a module connector with a first programmable voltage line, second programmable voltage line, and power control signal line. A first programmable voltage supply is coupled to the first programmable voltage line of the module connector, where based on a signal received at a first control input of the first programmable voltage supply, the first programmable voltage supply generates a voltage on the first programmable voltage line. A second programmable voltage supply is coupled to the second programmable voltage line of the module connector, where based on a signal received at a second control input of the second programmable voltage supply, the second programmable voltage supply generates a voltage on the second programmable voltage line. A power controller block is coupled to the power control signal line of the module connector, where based a signal on the power control signal line, the power controller block generates signals for the first and second control inputs.
In another embodiment, the invention is an electronic system including a module connector with a first programmable voltage line, second programmable voltage line, and at least one power control signal line. A first programmable voltage supply is coupled to the first programmable voltage line of the module connector, where based on a signal on the power control signal line, the first programmable voltage supply generates a voltage on the first programmable voltage line. A second programmable voltage supply is coupled to the second programmable voltage line of the module connector, where based on a signal on the power control signal line, the second programmable voltage supply generates a voltage on the second programmable voltage line.
In another embodiment, the invention is an electronic system including a first module connector with a first programmable voltage line, second programmable voltage line, and first power control signal line. A first power supply unit includes a first programmable voltage supply, connected to the first programmable voltage line of the first module connector, where based on a signal on the first power control signal line, the first programmable voltage supply generates a voltage on the first programmable voltage line. The first power supply unit includes a second programmable voltage supply, connected to the second programmable voltage line of the first module connector, where based on a signal on the first power control signal line, the second programmable voltage supply generates a voltage on the second programmable voltage line. A second module connector includes a third programmable voltage line, fourth programmable voltage line, and second power control signal line. A second power supply unit includes a third programmable voltage supply, connected to the third programmable voltage line of the second module connector, where based on a signal on the second power control signal line, the first programmable voltage supply generates a voltage on the third programmable voltage line. The second power supply unit includes a fourth programmable voltage supply, connected to the fourth programmable voltage line of the second module connector, where based on a signal on the second power control signal line, the second programmable voltage supply generates a voltage on the fourth programmable voltage line.
In another embodiment, the invention is an electronic system including an integrated circuit connector with a first programmable voltage line, second programmable voltage line, and power control signal line, where an integrated circuit connected to the integrated circuit connector will be electrically connected to receive voltages from the first and second programmable voltage lines. A first programmable voltage supply is connected to the first programmable voltage line of the integrated circuit connector, where based on a signal received at a first control input of the first programmable voltage supply, the first programmable voltage supply generates a voltage on the first programmable voltage line. A second programmable voltage supply is connected to the second programmable voltage line of the module connector, where based on a signal received at a second control input of the second programmable voltage supply, the second programmable voltage supply generates a voltage on the second programmable voltage line. A power controller block is connected to the power control signal line of the integrated circuit connector, where based on a signal received from the integrated circuit coupled to the integrated circuit connector on the power control signal line, the power controller block generates signals for the first and second control inputs.
In another embodiment, the invention is an electronic module including a connector to connect to an electronic system board, where the connector includes a supply voltage line and ground supply voltage line to connect to voltage sources provided by electronic system board. An integrated circuit is connected to a first programmable voltage line, second programmable voltage line, and power control signal line. A first programmable voltage supply is connected to the supply voltage line, ground supply voltage line, and the first programmable voltage line of the integrated circuit, where based on a signal received at a first control input of the first programmable voltage supply, the first programmable voltage supply generates a voltage on the first programmable voltage line. A second programmable voltage supply is connected to the supply voltage line, ground supply voltage line, and the second programmable voltage line of the module connector, where based on a signal received at a second control input of the second programmable voltage supply, the second programmable voltage supply generates a voltage on the second programmable voltage line. A power controller block is connected to the supply voltage line, ground supply voltage line, and power control signal line of the integrated circuit connector, where based on a signal received from the integrated circuit connected to the integrated circuit connector on the power control signal line, the power controller block generates signals for the first and second control inputs.
In another embodiment, the invention is a method of operating an electronic system having an integrated circuit requiring a plurality of operating voltages. A signal is provided from the integrated circuit to power controller circuitry. The signal is decoded using the power controller circuitry and first and second control signals are generated. The first control signal is received in a first programmable voltage generator, which generates a first voltage. The second control signal is received in a second programmable voltage generator, which generates a second voltage, different from the first voltage. The first and second voltages are provided to the integrated circuit.
In another embodiment, the invention is a method of operating an electronic system. A first module, having a master integrated circuit, is connected to the electronic system. A second module, having a slave integrated circuit, is connected to the electronic system. A common communication standard is determined to be usable by both the master and slave integrated circuits. Data is transferred from the master integrated circuit to a first programmable power supply to generate voltages for to configure the master integrated circuit to use the common communication standard. Data is transferred from the slave integrated circuit to a second programmable power supply to generate voltages to configure the slave integrated circuit to use the common communication standard.
In another embodiment, the invention is a method of operating an electronic system. A master integrated circuit is connected to the electronic system. A first module, having a first slave integrated circuit, is connected to the electronic system. A common communication standard is determined to be usable by both the master and first slave integrated circuits. Data is transferred from the master integrated circuit to a first programmable power supply to generate voltages for to configure the master integrated circuit to use the common communication standard. Data is transferred from the first slave integrated circuit to a second programmable power supply to generate voltages to configure the first slave integrated circuit to use the common communication standard.
In another embodiment, the invention is a method of operating an electronic system having a first integrated circuit requiring a plurality of operating voltages. A signal is provided from a second integrated circuit to power controller circuitry. The signal is decoded using the power controller circuitry and generating first and second control signals. The first control signal is received in a first programmable voltage generator, which generates a first voltage. The second control signal is received in a second programmable voltage generator, which generates a second voltage, different from the first voltage. The first and second voltages are provided to the first integrated circuit.
Other objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description and the accompanying drawings, in which like reference designations represent like features throughout the figures.